One of the greatest threats to wildlife, including increasingly rare neo-tropical songbirds, may be right in your own backyard. It's your pet cat.

To a cat, birds and small wildlife are fair and attractive game for sport and consumption. Nesting season is a particularly hazardous time, when cats can come upon a nest and destroy several birds at once.

The U.S. Census Bureau has estimated the number of pet cats in the United States at 60 million, not including semi-wild (feral) cats, according to Patricia Thompson, urban biologist with the Washington Department of Fish and Wildlife's (WDFW) regional office in Mill Creek. The combined total of pet cats and feral cats is probably closer to 100 million in this country, she added. A study of urban wildlife in Seattle in 1984 estimated there are more than 20 cats per block, Thompson said.

The impact of domestic cats on birds and wildlife has become so serious that the Seattle Audubon Society recently joined with WDFW and others in a "Cats Indoors" education effort.

"What the cat dragged in" is more than just an expression. What Fluffy or Felix deposits on doorsteps around the state are dead and mangled birds, small mammals, reptiles and amphibians. Many pet owners don't believe their cat is capable of killing anything, but they are often unaware of when and where their pet goes hunting. Often, prey animals are not killed outright, but are injured by the cat, let go, and later die.

Estimates vary on the number of birds and small animals killed by domestic cats. Many authorities are convinced that free-roaming cats (whether domestic or feral) have had significant impacts on local wildlife populations and are a contributing factor in the decline of neo-tropical songbirds. A Wisconsin study estimated that cats kill 39 million birds in that state each year.

Cats are introduced predators, not part of the natural ecosystem. Cats differ from wild predators in several ways:

Domestic cats are protected from disease, predation and competition– factors which limit the numbers of wild predators– so their numbers are artificially high and individuals are strong.

Pet cats are fed by their owners, which means the cat population does not decline along with prey species.

Domestic cat densities are not limited by available territory, no matter how much cat fighting you hear over the back fence.

Prey animals have not evolved to cope with introduced domestic cats and therefore have inadequate strategies for protecting themselves.

It only takes responsible pet ownership to save thousands of birds and other animals. Here's what to do:

Spay or neuter your cats— Animal shelters are full of domestic cats needing homes. Don't contribute to this problem by allowing your cat to breed.

Keep your cat indoors— Indoor cats are significantly healthier than outdoor pets (ask your veterinarian). For ideas on how to keep cats happy indoors, contact your local Humane Society or, in the Puget Sound area, the Progressive Animal Welfare Society (PAWS). Informational brochures on keeping cats indoors also are available at WDFW offices across the state. If you want your cat to have outdoor time, build an enclosed outdoor space for it to play in. For information on design and use, visit the American Bird Conservancy website.

Remember that belled or declawed cats still can kill or injure wildlife– Birds and other wildlife may not recognize a bell as an alarm signal; even if they do, cats are stealthy hunters and often learn how to silence bells.

Don't make a wild bird a "sitting duck"— Place bird feeders carefully if you see or suspect that cats are roaming in your backyard. The safest place is in an open area where birds can see approaching cats.

Don't dispose of unwanted cats by releasing them— Dumping unwanted cats is never acceptable, even in rural areas or "cat colonies."

Don't feed stray cats— If you truly want to rescue a homeless cat, take it into your home, or to an animal shelter.